In the past, malware such as email viruses, Trojan horses, worms, adware, and spyware were detectible by some form of antivirus software. When executed, worms and Trojan horses, like viruses, may cause harm to a computer system's stored data, functional performance, or networking throughput. Some viruses and other malware have symptoms noticeable to the computer user, but many are surreptitious. A type of virus that is causing much anxiety in the scientific community due to its ability to evade detection is a type of virus that gets into a specific result data file, corrupting or changing only one value or string at a time. This type of virus then stops and even erases itself, or targets disabling program files located in a document storage unit. Other similar viruses get into banking documents and try to steal money. These viruses can cause much danger and harm to society, for example, by altering medical records, causing financial devastation, or altering output files from engineering programs.
The architecture of the computer was not originally designed for defending against virus intrusions from the Internet. Therefore, what is needed is an improved mechanism and technique to detect the presence of virus intrusions in order to give the user a higher degree of confidence in the security of their valuable documents.